Hypoxia‐induced expression of phosphoglycerate mutase B in fibroblasts

Abstract

Molecular oxygen (O 2 ) is essential for aerobic organisms. Exposure of tissues or cells to hypoxia induces a variety of adaptive or pathogenic responses. To understand the mechanism and processes of cellular response to hypoxia, we exposed fetal rat lung fibroblasts to hypoxia (pO 2 Ϸ5 Pa) and screened the hypoxia-responsible gene by the differential display method. Exposure of the cells to hypoxia activated the phosphoglycerate mutase B (PGM-B) gene, resulting in the induction of PGM enzymatic activity, concomitant with elevations of PGM-B mRNA and protein levels. The mRNA level was elevated linearly with decreases in partial O 2 pressure, indicating a 2Ϫ3-fold increase in these levels after 16 h hypoxia. Up-regulation of PGM mRNA by hypoxia was obvious after 8 h exposure, reached its peak after 16 h, persisting for 40 h and returned to the basal level after reoxygenation at 20% O 2 for 16 h. Run-on and stability assays indicated that PGM-B expression is regulated mainly at the transcriptional step. These results suggest that the induction of PGM-B may contribute to the regulation of the glycolytic flux under reduced O 2 tension and play a role in the adaptation of cells to hypoxia.Keywords : hypoxia ; reoxygenation ; phosphoglycerate mutase B; differential display; fibroblast.Molecular oxygen (O 2 ) is essential for aerobic organisms. within minutes, after hypoxic exposure. It is generally accepted Principally, O 2 participates in oxidation-reduction reactions in that the Pasteur effect relates to an acute increase in the intracelthe biosystem and functions as a terminal electron acceptor of lular phosphofructokinase activity resulting from changes in the mitochondrial oxidative phosphorylation in the production of en-concentration of low molecular-mass allosteric effectors, alergy [1]. O 2 is also the means of oxygenation by which bioactive though other alterations in enzyme activities participate [6,7]. materials, such as steroid hormones and prostaglandins, are syn-Chronic hypoxic exposure of a variety of tissues and cells results thesized. Furthermore, desaturation of fatty acid and hydroxyla-in a substantial additional increase in the rate of glycolysis betion of proline also require O 2 for enzymatic reactions. The par-yond that produced by the Pasteur effect [8]. tial O 2 pressure needed for enzymatic reactions varies depending Enzymatic activities of all glycolytic components of epitheon the type of enzyme [2].lial and mesenchymal cell lines are coordinately enhanced by Ischemia and/or hypoxia cause a reduced tension of O 2 in chronic hypoxia [9,10]. Although the detailed mechanism by cells and tissues. In an acute response to reduced O 2 concentra-which the glycolytic activity is substantially increased after tions in tissues, hyperventilation is the primary systemic adapta-chronic hypoxia is unclear, some glycolytic enzymes, but not tion. It results in an increase in arterial O2 tension, enhancing all, are up-regulated at transcription levels. Steady-state mRNA delivery of O 2 to distal tissues [3]....

Proteomic analysis of epicardial and subcutaneous adipose tissue reveals differences in proteins involved in oxidative stress

“…Although PGAM1 may contribute to an increase in glycolytic flux in response to hypoxia, PGAM1 levels increasing in fibroblasts cultured in hypoxic conditions (31), increased glycolysis has also been associated with protection against oxidative stress (15). PGAM1 has several phosphorylation sites.…”

Hypoxic Induction of Prolyl 4-Hydroxylase α(I) in Cultured Cells

“…At subconfluence, cells were exposed to hypoxia or treated with chemicals. Exposures of cells to hypoxia were performed as described previously (9). In some experiments, 200 M ascorbic acid was added to the medium.…”

“…Differential Display and Transcriptional Run-on Assay-We followed the fluorescent differential display method developed by Ito et al (20) with several modifications, as described in a previous paper (9). Transcriptional run-on assay was performed as described previously (9).…”

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“…3B). Edman degradation sequence analysis identified three N-terminal sequences: 30 FEIALP, 369 KFVPGC, and 370 FVPGC. The first of these has previously been reported by us as the amino-terminal of 135 kDa CDCP1 (2), generated through removal of the 29 residue signal peptide (Fig.…”